1. Chapter 10c
Sensory Physiology

2. Vestibular apparatus Semicircular canals Otolith organs
The Ear: Equilibrium
Vestibular apparatus
Semicircular canals
Otolith organs
Equilibrium pathways

3. The Vestibular Apparatus
A series of interconnected fluid-filled chambers
Provides information about movement and position in space

4. Anatomy Summary: The Vestibular Apparatus
SEMICIRCULAR CANALS
(a)
Superior
Horizontal
Posterior
Cochlea
Cristae within ampulla
Utricle
Saccule
Maculae
Figure 10-25a

5. Anatomy Summary: The Vestibular Apparatus
Posterior canal (head tilt)
Superior canal (nod for “yes”)
Left
right
Horizontal canal (shake head for “no”)
(b)
Figure 10-25b

6. Anatomy Summary: The Vestibular Apparatus
Cupula
Endolymph
Hair cells
Supporting cells
Nerve
(c)
Figure 10-25c

7. Anatomy Summary: The Vestibular Apparatus
Hair cells
Gelatinous otolith membrane
Otoliths are crystals that move in response to gravitational forces.
Nerve fibers
(d) Macula
Figure 10-25d

8. Transduction of Rotational Forces in the Cristae
The semicircular canals sense rotational acceleration
Brush moves right
Cupula
Bone
Endolymph
Stationary board
Bristles bend left
Hair cells
Bone
Direction of rotation of the head
When the head turns right, endolymph pushes the cupula to the left.
Figure 10-26

9. Otoliths Move in Response to Gravity or Acceleration
Figure 10-27a

10. Otoliths Move in Response to Gravity or Acceleration
Figure 10-27b

11. Dynamic Equilibrium and the crista ampullaris

12. Meniere's disease
Vincent van Gogh, whose artistic brilliance and supposed madness have made him a focus of popular fascination, suffered not from epilepsy or insanity but from Meniere's disease,

13. Central Nervous System Pathways for Equilibrium
Cerebral cortex
Thalamus
Reticular formation
Vestibular branch of vestibulocochlear nerve (VIII)
Cerebellum
Somatic motor neurons controlling eye movements
Vestibular apparatus
Vestibular nuclei of medulla
Figure 10-28

14. Photoreceptors transduce light energy
The Eye and Vision
Light enters the eye
Focused on retina by the lens
Photoreceptors transduce light energy
Electrical signal
Processed through neural pathways

15. External Anatomy of the Eye
Muscles attached to external surface of eye control eye movement.
Lacrimal gland secretes tears.
Upper eyelid
Sclera
Pupil
Iris
Lower eyelid
The orbit is a bony cavity that protects the eye.
Nasolacrimal duct drains tears into nasal cavity.
Figure 10-29

16. Anatomy Summary: The Eye
Zonules
Lens
Optic disk (blind spot)
Canal of Schlemm
Aqueous humor
Central retinal artery and vein
Cornea
Optic nerve
Pupil
Fovea
Iris
Macula
Vitreous chamber
(b)
Retina
Ciliary muscle
Sclera is connective tissue.
(a) Sagittal section of the eye
Figure 10-30

17. Anatomy Summary: The Eye
Zonules
Lens
Optic disk (blind spot)
Canal of Schlemm
Central retinal artery and vein
Aqueous humor
Cornea
Optic nerve
Pupil
Fovea
Iris
Vitreous chamber
Retina
Ciliary muscle
Sclera is connective tissue.
(a) Sagittal section of the eye
Figure 10-30a

18. Anatomy Summary: The Eye
Optic disk (blind spot)
Central retinal artery and vein
Fovea
Macula
(b)
Figure 10-30b

19. Neural Pathways for Vision and the Pupillary Reflex
(a) Dorsal view
Optic tract
Eye
Optic chiasm
Optic nerve
Figure 10-31a

20. Neural Pathways for Vision and the Pupillary Reflex
(b) Neural pathway for vision, lateral view
Eye
Optic nerve
Optic chiasm
Optic tract
Lateral geniculate body (thalamus)
Visual cortex (occipital lobe)
Figure 10-31b

21. Neural Pathways for Vision and the Pupillary Reflex
(c) Collateral pathways leave the thalamus and go to the midbrain.
Optic nerve
Optic chiasm
Optic tract
Lateral geniculate body (thalamus)
Visual cortex (occipital lobe)
Eye
Light
Midbrain
Cranial nerve III controls pupillary constriction.
Figure 10-31c

22. Light enters the eye through the pupil
Size of the pupil modulates light
Photoreceptors
Shape of lens focuses the light
Pupillary reflex
Standard part of neurological examination

23. Refraction of Light
Figure 10-32a

24. Refraction of Light
Figure 10-32b

25. Optics
Figure 10-33a

26. Optics
Figure 10-33b

27. Optics
Figure 10-33c

28. Accommodation
Accommodation is the process by which the eye adjusts the shape of the lens to keep objects in focus
Cornea
Iris
Lens
Ligaments
Ciliary muscle
(a) The lens is attached to the ciliary muscle by inelastic ligaments (zonules).
Figure 10-34a

29. Accommodation Ciliary muscle relaxed Lens flattened Cornea
Ligaments pulled tight
(b) When ciliary muscle is relaxed, the ligaments pull on and flatten the lens.
Figure 10-34b

30. Accommodation Ciliary muscle contracted Lens rounded Ligaments slacken
(c) When ciliary muscle contracts, it releases tension on the ligaments and the lens becomes more rounded.
Figure 10-34c

31. Common Visual Defects
Figure 10-35a

32. Common Visual Defects
Figure 10-35b

33. The Electromagnetic Spectrum
Figure 10-36

34. Anatomy Summary: The Retina
Horizontal cell
Amacrine cell
Light
Ganglion cell
Neurons where signals from rods and cones are integrated
Cone (color vision)
Bipolar cell
Rod (monochromatic vision)
(d) Retinal photoreceptors are organized into layers.
Figure 10-37d

35. Phototransduction
Figure 10-38

36. Photoreceptors: Rods and Cones
PIGMENT EPITHELIUM
Old disks at tip are phagocytized by pigment epithelial cells.
Melanin granules
OUTER SEGMENT
Visual pigments in membrane disks
Disks
Disks
Connecting stalks
INNER SEGMENT
Mitochondria
Location of major organelles and metabolic operations such as photopigment synthesis and ATP production
Rhodopsin molecule
Cone
Rods
Retinal
Opsin
SYNAPTIC TERMINAL
Synapses with bipolar cells
Bipolar cell
LIGHT
Figure 10-39

37. Photoreceptors: Rods and Cones
PIGMENT EPITHELIUM
Old disks at tip are phagocytized by pigment epithelial cells.
Melanin granules
OUTER SEGMENT
Disks
Visual pigments in membrane disks
Disks
Connecting stalks
Figure (1 of 2)

38. Photoreceptors: Rods and Cones
INNER SEGMENT
Mitochondria
Location of major organelles and metabolic operations such as photopigment synthesis and ATP production
Rhodopsin molecule
Cone
Rods
Retinal
Opsin
SYNAPTIC TERMINAL
Synapses with bipolar cells
Bipolar
cell
LIGHT
Figure (2 of 2)

39. Light Absorption of Visual Pigments
Figure 10-40

40. Phototransduction in Rods
(a) In darkness, rhodopsin is inactive, cGMP is high, and CNG and K+ channels are open.
Pigment epithelium cell
Disk
Transducin (G protein)
Inactive rhodopsin (opsin and retinal)
cGMP levels high
Ca2+
CNG channel open
Na+ K+
Membrane potential in dark = –40mV
Rod
Tonic release of neurotransmitter onto bipolar neurons
Figure 10-41a

41. Phototransduction in Rods
(b) Light bleaches rhodopsin. Opsin decreases cGMP, closes CNG channels, and hyperpolarizes the cell.
Activated retinal
Opsin (bleached pigment)
Activates transducin
Cascade
Decreased cGMP
Ca2+
Na+
CNG channel closes K+
Membrane hyperpolarizes to –70 mV
Light
Neurotransmitter release decreases in proportion to amount of light.
Figure 10-41b

42. Phototransduction in Rods
(c) In the recovery phase, retinal recombines with opsin.
When light activates rhodopsin, a second-messenger cascade is initiated through transducin
Retinal converted to inactive form
Retinal recombines with opsin to form rhodopsin.
Figure 10-41c

43. Ganglion Cell Receptive Fields
Figure 10-42

44. Visual Fields and Binocular Vision
zone
Left
visual
field
Right
visual
field
Optic
chiasm
Optic nerve
Optic tract
Lateral
geniculate body
(thalamus)
Visual cortex
Figure 10-43

45. General properties Somatic senses Summary
Four types of sensory receptors
Adequate stimulus, threshold, receptive field, and perceptual threshold
Modality, localization, intensity, and duration
Somatic senses
Four modalities, second sensory neurons, and somatosensory cortex
Nociceptors, spinal reflexes, and pain

46. The ear: hearing and equilibrium The eye and vision
Summary
Chemoreception
Olfaction and taste
The ear: hearing and equilibrium
The eye and vision
Retina, pupil, ciliary muscle, and photoreceptors